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Dear Ladies and Gentlemen,

Webasto as a supplier of rooflites, backlites and especially as
producer of glazing products like polycarbonate rooflites (e.g.
Smart ForTwo) will object to the current draft of the CARB´s
regulation “Cool Cars Standards and Test Procedures”.
The current draft of CARB’s regulation (May 2009) could have the
effect of precluding polycarbonate glazing, which would forgo the
substantial GHG reduction potential that can be achieved by
replacing glass with lighter weight alternative glazing materials.
The density of polycarbonate is half of glass that means you can
get a weight benefit up to 50% by using polycarbonate for glazing.
In the case of the Smart ForTwo rooflite glazing the weight
reduction is 42%! And weight reduction is  one of the key figure to
reduce fuel consumption and as a result CO2 emission! The GHG
emissions reduction due to weight reduction by using polycarbonate
is comparable to those CARB proposes to achieve with glass solar
reflective technology.
The EPA Federal Test Procedure has confirmed that reducing vehicle
weight by 10% results in a 7% fuel economy improvement and the
consequent GHG emission benefits.  (See page 19 of Cheah et al.
“Factor of Two: Halving the Fuel Consumption of New U.S.
Automobiles by 2035” (2009) at
http://web.mit.edu/sloan-auto-lab/research/beforeh2/files/cheah_factorTwo.pdf


Webasto is proposing that CARB amend the regulation in the way
that polycarbonate will be add as an alternative glazing material
and have different limit values for Tts to fulfill, because the GHG
reduction benefit due to weight reduction is already comparable to
those with glass solar reflective technology.
The available solar reflecting technology is not currently
compatible with polycarbonate glazing and the limit values of Tts
are a high engineered barrier, but if you combine the GHG reduction
benefit due to weight reduction and the reduction benefit of, for
example IR-absorbing polycarbonate, the total GHG reduction is much
higher than those with glass solar reflective technology only!
Proposal as an example for §95603/4 (1/2/3/5/6 should be
similar):
(4) For 2012 and subsequent model year vehicles, the rooflite(s),
if any, must have a Tts less than or equal to thirty percent (30%),
referenced to a glazing of 4 millimeter thickness.  For 2012 and
subsequent model year vehicles, the Alternative Glazing Material
rooflite(s), if any, composed of polycarbonate must have a Tts less
than or equal to fifty percent (50%), referenced to a glazing of 4
millimeter thickness.  
It is very important to keep the marketplace open for innovative
materials/products, which helps reducing fuel consumption/GHG
emission, and competition!

Kind regards,

Webasto AG

i.V. Jochen Walz      i.A. Andreas Lang